Conventional spatial optical switch is comprised of: an input waveguide that inputs an optical signal; a slab waveguide that distributes the optical signal to an arrayed waveguide; an arrayed waveguide that is equipped with a triangular-shaped electrode for performing current injection or voltage application in order to change refractive index; a slab waveguide that couples outputted light from the arrayed waveguide to an output waveguide; and a plurality of output waveguides that output optical signals (see Patent Literature 1: Japanese Patent Application Laid-Open No. 2002-72157, for example). This conventional spatial optical switch has a plurality of output waveguides arranged in parallel, which spatially distribute an input optical signal of one wavelength by a control signal to be applied to an electrode, and couples a signal of one wavelength to different output waveguides.